Effects of combined training on nonshivering thermogenic activity of muscles in individuals with overweight and type 2 diabetes

Abstract Background Increased thermogenic activity has shown to be a promising target for treating and preventing obesity and type 2 diabetes (T2DM). Little is known about the muscular influence on nonshivering thermogenesis (NST), and it remains unclear whether physical training and potential metabolic improvements could be associated with changes in this type of thermogenic activity. Objective The present study aimed to assess muscular NST activity in overweight and T2DM before and after a combined training period (strength training followed by aerobic exercise). Methods Nonshivering cold‐induced 18‐fluoroxyglucose positron emission computed tomography (18F‐FDG PET/CT) was performed before and after 16 weeks of combined training in 12 individuals with overweight and T2DM. The standard uptake value (SUV) of 18F‐FDG was evaluated in skeletal muscles, the heart and the aorta. Results Muscles in the neck region exhibit higher SUV pre‐ and posttraining. Furthermore, a decrease in glucose uptake by the muscles of the lower and upper extremities and in the aorta was observed after training when adjusted for brown adipose tissue (BAT). These pre–post effects are accompanied by increased cardiac SUV and occur concurrently with heightened energy expenditure and metabolic improvements. Conclusions Muscles in the neck region have greater metabolic activity upon exposure to cold. In addition, combined training appears to induce greater NST, favoring the trunk and neck region compared to limbs based on joint work and adaptations between skeletal muscles and BAT.